feat(ci): apply ADR-0022 branch shape check and issue link

[ss-o]

Summary

decisions/0022-issue-traceability-on-pull-requests.md was accepted in
z-shell/.github#594 and
implemented for the organization repository in z-shell/.github#600 and
z-shell/.github#601. This repository carries the same commit-lint.yml jobs
with their patterns inlined, so it needs the matching change or the two copies
drift, which ADR-0022 step 5 explicitly warns about.

What changes

1. Validate Branch Name becomes a shape check. The identifier stops being
   mandatory:

   ^((feature|bug|hotfix)-[1-9][0-9]*(-[a-z0-9]+)*
    |(feat|fix|perf|refactor|docs|test|build|ci|style|chore|revert|feature|bug|hotfix)/[a-z0-9]+(-[a-z0-9]+)*)$
   

   feature-<id> stays valid and recommended. next keeps its
   persistent-integration exemption under
   decisions/0019-trunk-on-main-default.md, and the automation prefixes are
   unchanged.

2. Validate Issue Link is added, matching the organization copy. It passes
   on an automation branch, a meta:no-issue label, or an issue reference in
   the pull-request body, and reports which applied. It reads only the
   pull_request event payload, so it needs no token.

Prerequisite

meta:no-issue has to exist as a label in this repository before the exemption
path is usable. It is declared in the organization catalog at
z-shell/.github:lib/labels.yml.

Note

code is not in the decisions/0003-conventional-commits.md type set, so
code/ branches remain rejected here as they do in the organization
repository. That was the accepted scope of ADR-0022.

Parent: z-shell/.github#595

[ss-o]

Resolved by #490, squash-merged to next as f8f3bdfc.

Validate Branch Name is now a shape check and Validate Issue Link is in place. Closing manually because this repository's default branch is main and the pull request merged to next, so the Closes keyword does not fire (z-shell/.github#523). The change reaches main at the next promotion.

Still outstanding here: meta:no-issue reaches this repository through label sync, so the exemption path is unusable until then. Nothing breaks in the meantime; the check falls through to the body reference.